The invention relates to a DC-DC converter system and to a DC voltage supply system and a printed circuit board for a DC-DC converter system, and is directed, in particular, to a DC-DC converter system for use in a vehicle for supplying electric switching units and/or control units with different stabilized DC voltages.
In vehicles, in particular passenger cars, electric switching units and control units are supplied from the low-voltage vehicle electrical system (approximately 12 volts) with an input voltage which varies greatly due to input networks (e.g., switches, protective circuit, filters) connected therebetween. In general, the full reliability of the electric switching units and control units is required for an input voltage which varies in the range from approximately 6 volts to 27 volts DC. This large input voltage range is covered by means of electronic power circuits, in particular DC-DC converters or DC voltage controllers, which convert the varying input voltage into stabilized DC voltages having predefined, individual voltage values and supply the electric switching units and control units therewith.
One known approach for supplying the electric switching units and control units with a stabilized DC voltage from the vehicle electrical system consists of increasing the varying input voltage with the aid of a step-up converter or step-up controller, which is also referred to as a boost converter and is illustrated in FIG. 4 by way of example, to a stabilized, increased supply voltage of 30 volts, for example, with the aid of a control device and a switching device.
In addition to the increased voltage, a stabilized 12-volt DC voltage is usually also required, as the further supply voltage, which can be generated according to two known concepts. According to one first known concept, the 12-volt DC voltage is generated directly from the stabilized, increased supply voltage (e.g., 30 volts) with the aid of a linear controller installed downstream from the step-up converter. The great power loss resulting from the high voltage difference of the voltage conversion (e.g., from 30 volts to 12 volts) is disadvantageous in this case. According to one second known concept, the varying input voltage is fed not only to the aforementioned step-up converter, but also to a SEPIC converter (SEPIC: Single Ended Primary Inductance Converter)—which is illustrated in FIG. 5 by way of example—for generating the second supply voltage (e.g., 12 volts) which can be lower or higher than the varying input voltage. One disadvantage of this second concept is that the SEPIC converter, as is also the case with the step-up converter, requires a dedicated control device and switching device, for example designed as a controlled MOSFET, which results in a need for more space and also results in higher costs and possible EMC problems due to the additional switching processes.